He is described as about 6ft tall with a shaven head and a brown and red beard.
When last seen, he was wearing blue jeans, a navy jumper and a blue and yellow hat, and was carrying a green tent.
Orr is from Leslie in Fife and it is not known if he has travelled back to the area.
He has a Honda CRV car with the registration SL59 SWJ.
Insp Claire Walker said officers were becoming increasingly concerned as he had not contacted his family.
She added that he was a keen walker and may be travelling along the Annandale Way.
